Two-level stringification in C macros: what does this program print? #include<stdio.h> #define str(x) #x #define Xstr(x) str(x) #define oper multiply int main() { char *opername = Xstr(oper); printf("%s\n", opername); return 0; }

Introduction / Context:
This checks knowledge of macro stringification and why a two-level macro is needed to stringify another macro’s replacement text instead of its name. It is a classic pattern used in build-time banners and generated identifiers.

Given Data / Assumptions:

• #define oper multiply (token replacement)
• #define str(x) #x and #define Xstr(x) str(x)
• Printing opername with printf.

Concept / Approach:
Single-level stringification str(oper) would yield the literal "oper". However, two-level expansion Xstr(oper) first expands oper to multiply, then stringifies to "multiply". Therefore, the program prints multiply (without quotes).

Step-by-Step Solution:

Verification / Alternative check:
Change oper to divide and recompile; you will see divide printed, proving two-step expansion occurs.

Why Other Options Are Wrong:

Common Pitfalls:
Expecting # to expand its argument before stringifying; it does not without the two-level trick.

Final Answer:
multiply.